1. Field of the Invention
The present invention relates to a video data recording/reproducing apparatus, which records and reproduces video data, and a video data management method for used in the apparatus.
2. Description of the Related Art
In recent years, a variety of video data recording/reproducing apparatus have been developed, which are capable of recording and reproducing video data such as TV broadcast programs. In this type of video data recording/reproducing apparatuses, HDDs (hard disk drives) have begun to be used as video data recording media in place of conventional video tapes.
If a broadcast program is recorded on the HDD, high-speed finding of a start-point of the recorded broadcast program is enabled. In addition, by recording the broadcast program on the HDD, a so-called time-shift function (also known as time-slip function) is realized. The time-shift function is such a function that while a broadcast program is being recorded, the broadcast program that is being recorded can be reproduced from, e.g. its start point. Moreover, unlike video tapes, the HDD does not require an operation for finding a start-point of recording. In the state in which the HDD has a sufficient free space, recording can be started immediately.
Although the capacity of the HDD for use in video data recording/reproducing apparatuses has increased year by year, it is not limitless. Even in the video data recording/reproducing apparatus with a large-capacity HDD, an operation for deleting already recorded program data is required in order to keep a free space for new recording.
In a mobile information processing apparatus such as a PDA (Personal Digital Assistant), technology for effectively utilizing limited memory resources is adopted.
Jpn. Pat. Appln. KOKAI Publication No. 2001-350631 discloses a technique wherein in a case where a free space in a memory of a mobile information processing apparatus is so small that a new application program cannot be downloaded in the mobile information processing apparatus, an application program that is stored in the memory of the mobile information processing apparatus is temporarily saved in a server. In this apparatus of KOKAI 2001-350631, after execution of a downloaded new application program is finished, this application program is deleted from the memory and the application program that has been saved in the server is restored to the memory.
Jpn. Pat. Appln. KOKAI Publication No. 2000-13745 discloses an apparatus wherein video data recorded on the HDD is automatically compressed to keep a sufficient free space in the HDD. In this apparatus, in accordance with an elapsed time from recording of video data, the compression ratio for compressing the video data is altered.
In general terms, however, the quality of video data becomes lower in accordance with an increase in compression ratio of the video data.
If the technique of KOKAI 2001-350631, in which the program that has temporarily been saved in the server is restored to the memory, is applied to a video data recording/reproducing apparatus, the following situation would occur: each time video data that has temporarily been saved in the server is restored, other data that is stored in the HDD needs to be saved in the server. In this case, two data transfer operations need to be executed. That is, data transfer from the server to the video data recording/reproducing apparatus and data transfer from the video data recording/reproducing apparatus to the server are required. In usual cases, the data size of video data is much greater than that of program data. The two data transfer operations cause an increase in load that is needed for communication processing in the video data recording/reproducing apparatus.